Facilitating and restraining virus infection using cell-attachable soluble viral receptors.

SARS-CoV-2 uses the receptor binding domain (RBD) of its spike protein to recognize and infect host cells by binding to the cell surface receptor angiotensin converting enzyme 2 (ACE2). The ACE2 receptor is composed of peptidase domain (PD), collectrin-like domain, transmembrane domain, and short cytoplasmic domain, and may exist as a dimer on cell surface. The RBD binding site is located atop of the ACE2 PD, but the involvement of other domains in virus infection is uncertain. We found that the ACE2 PD alone, whether anchored to cell membrane via a glycosylphosphatidylinositol anchor or attached to another surface protein, is fully functional as a receptor for spike-mediated cell fusion and virus infection. However, for ACE2 to function as the viral receptor, the RBD binding site must be positioned in close proximity to the cell membrane. Elevating the surface height of ACE2 using long and rigid protein spacers reduces or eliminates cell fusion and virus infection. Moreover, we found that the RBD-targeting neutralizing antibodies, nanobodies, and de novo designed miniprotein binders, when present on cell surface, also act as viral receptors, facilitating cell fusion and virus infection. Our data demonstrate that RBD binding and close membrane proximity are essential properties for a receptor to effectively mediate SARS-CoV-2 infection. Importantly, we show that soluble RBD-binders can be engineered to make cells either susceptible or resistant to virus infection, which has significant implications for antiviral therapy and various virus-mediated applications.

Integrin α5ß1 contributes to cell fusion and inflammation mediated by SARS-CoV-2 spike via RGD-independent interaction.

The Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus infects host cells by engaging its spike (S) protein with human ACE2 receptor. Recent studies suggest the involvement of integrins in SARS-CoV-2 infection through interaction with the S protein, but the underlying mechanism is not well understood. This study investigated the role of integrin α5ß1, which recognizes the Arg-Gly-Asp (RGD) motif in its physiological ligands, in S-mediated virus entry and cell-cell fusion. Our results showed that α5ß1 does not directly contribute to S-mediated cell entry, but it enhances S-mediated cell-cell fusion in collaboration with ACE2. This effect cannot be inhibited by the putative α5ß1 inhibitor ATN-161 or the high-affinity RGD-mimetic inhibitor MK-0429 but requires the participation of α5 cytoplasmic tail (CT). We detected a direct interaction between α5ß1 and the S protein, but this interaction does not rely on the RGD-containing receptor binding domain of the S1 subunit of the S protein. Instead, it involves the S2 subunit of the S protein and α5ß1 homo-oligomerization. Furthermore, we found that the S protein induces inflammatory responses in human endothelial cells, characterized by NF-κB activation, gasdermin D cleavage, and increased secretion of proinflammatory cytokines IL-6 and IL-1ß. These effects can be attenuated by the loss of α5 expression or inhibition of the α5 CT binding protein phosphodiesterase-4D (PDE4D), suggesting the involvement of α5 CT and PDE4D pathway. These findings provide molecular insights into the pathogenesis of SARS-CoV-2 mediated by a nonclassical RGD-independent ligand-binding and signaling function of integrin α5ß1 and suggest potential targets for antiviral treatment.

Rabies Vaccine Hesitancy and Deaths Among Pregnant and Breastfeeding Women - Vietnam, 2015-2016.

Human rabies deaths are preventable through prompt administration of postexposure prophylaxis (PEP) with rabies immune globulin and rabies vaccine after exposure to a rabid animal (1); there are no known contraindications to receiving PEP (1,2). Despite widespread availability of PEP in Vietnam, in 2015 the Ministry of Health (MoH) received reports of pregnant and breastfeeding women with clinically diagnosed rabies. MoH investigated factors associated with these rabies cases. MoH found that, during 2015-2016, among 169 cases reported in Vietnam, two probable cases of rabies were reported in breastfeeding mothers and four in pregnant women, all of whom had been bitten by dogs. All six patients died. Three of the four pregnant women had cesarean deliveries. One of the three newborns died from complications believed to be unrelated to rabies; the fourth pregnant woman contracted rabies too early in pregnancy for the fetus to be viable. Two of the patients sought care from a medical provider or traditional healer; however, none sought PEP after being bitten. In each case, families reported the patient's fear of risk to the fetus or breastfed child as the primary barrier to receiving PEP. These findings highlight the need for public health messaging about the safety and effectiveness of PEP in preventing rabies among all persons with exposures, including pregnant and breastfeeding women.

Integrin αIIbß3-Dependent ERK Signaling Is Regulated by Src and Rho Kinases in Both Leu33 and Pro33 Polymorphic Isoforms.

Platelet integrin αIIbß3 possesses a Leu/Pro polymorphism at residue 33 (Leu33/HPA-1a or Pro33/HPA-1b). The Pro33 isoform has been suggested to exhibit prothrombotic features. αIIbß3-expressing CHO (Chinese hamster ovary) cells on immobilized fibrinogen show activation of the MAP kinase family member ERK2, with an enhanced ERK2 activity in Pro33 cells compared to Leu33 cells. In our present work, we examined how the Leu/Pro polymorphism modulates the ERK2 activation stimulated by 2 differently triggered outside-in signalings. We either treated the CHO cells with Mn2+ or allowed them to adhere to fibrinogen. Moreover, we studied which signaling cascades are involved in ERK2 activation. In contrast to immobilized fibrinogen, Mn2+ did not significantly increase ERK2 activation. However, Mn2+ had a synergistic effect on ERK2 phosphorylation when combined with immobilized fibrinogen. Pro33 cells adherent to fibrinogen exhibited a significantly greater ERK2 activity than Leu33 cells in the presence of Mn2+, which peaked after 10 min of adhesion. Our data showed that Src family and rho kinases play a crucial role in the integrin αIIbß3-dependent outside-in signaling to ERK2.

Sex hormone levels as determinants of bone mineral density and osteoporosis in Vietnamese women and men.

This study sought to investigate the prevalence of osteoporosis and the role of sex hormone levels in the determination of bone mineral density (BMD) and osteoporosis in a Vietnamese population of women and men. The cross-sectional study involved 269 women and 222 men aged 13-83 years, who were randomly selected from urban and rural areas in northern Vietnam. Serum concentrations of estradiol and testosterone were analyzed, and BMD was measured by dual X-ray absorptiometry. We found that the prevalence of osteoporosis in postmenopausal women was 18, 17, and 37 % for the femoral neck, total hip, and lumbar spine, respectively. For men aged 50 years or older, the corresponding values were 8, 7, and 12 %. In men, the most important predictors of BMD for the femoral neck and total hip were age, body mass index, and serum levels of estradiol. For the BMD of the lumbar spine, testosterone also had a significant influence. Determinants of osteoporosis in men for the total hip and lumbar spine were age, weight, and serum concentrations of estradiol and testosterone. In postmenopausal women, age, weight, and residence (urban vs rural) were the most important predictors of BMD and osteoporosis. For all women (including those of reproductive age), serum levels of estradiol were also significant. These data suggest that the prevalence of osteoporosis in the Vietnamese population is high also in men, and that estradiol levels are essential for bone mass in both men and women. The results should have clinical implications and increase awareness of an important health issue within Vietnamese society.

Shear-related fibrillogenesis of fibronectin.

Biomechanical forces can induce the transformation of fibronectin (Fn) from its compact structure to an extended fibrillar state. Adsorption of plasma proteins onto metallic surfaces may also influence their conformation. We used a cone-plate rheometer to investigate the effect of shear and stainless steel on conformational changes of Fn. In control experiments, cones grafted once or twice with polyethylene glycol were used. Plasma Fn was added at concentrations of 50 or 100 µg/ml to bovine serum albumin (BSA)- or Fn-coated plates and subsequently exposed to dynamic shear rates stepwise increasing from 50 to 5000 s-1 within 5 min and subsequently decreasing from 5000 to 50 s-1 within 5 min. The viscosity (mPa s) of Fn solutions was recorded over 10 min. Upon exposure to shear, the viscosity in the sample increased, suggesting conformational changes in Fn. Western blotting and densitometric analyses demonstrated that conformational changes of plasma Fn depended both on shear and protein concentration. However, there was no significant difference in fibril formation between BSA- or Fn-coated plates, suggesting that physical properties of stainless steel and biomechanical forces such as shear can affect the molecular structure of Fn. Our model may provide useful information of surface- and flow-induced alterations of plasma proteins.

Appendicular Lean Mass and Frailty among Geriatric Outpatients.

The objective of this observational study was to examine the association between appendicular lean mass and frailty in adults aged 60 years and older. This study was conducted in the Outpatient Department of the National Geriatric Hospital in Hanoi, Vietnam. Appendicular lean mass (kg) was assessed by using Dual energy X-ray absorptiometry scans. Frailty was defined according to Fried's frailty criteria. A total of 560 outpatients were included in the study, with a mean age of 70 years. The prevalence of frailty was 12.0%. Frail patients had significantly lower appendicular lean mass compared with non-frail outpatients (9.6 ± 2.0 kg vs. 11.7 ± 3.1 kg, p<0.001). On multivariable logistic regression models, higher appendicular lean mass was associated with significantly reduced odds for frailty (adjusted OR = 0.74, 95%CI 0.59 - 0.93). These findings suggest that the assessment of appendicular lean mass should be considered in older patients attending outpatient geriatric clinics.

Paxillin binding to the PH domain of kindlin-3 in platelets is required to support integrin αIIbß3 outside-in signaling.

BACKGROUND: Kindlin-3 is essential for supporting the bidirectional signaling of integrin αIIbß3 in platelets by bridging the crosstalk between integrin αIIbß3 and the cytoplasmic signaling adaptors. OBJECTIVE: In this study, we identified a previously unrecognized paxillin binding site in the pleckstrin homology (PH) domain of kindlin-3 and verified its functional significance. METHODS: Structure-based approaches were employed to identify the paxillin binding site in the PH domain of kindlin-3. In addition, the bidirectional signaling of integrin αIIbß3 were evaluated in both human and mouse platelets. RESULTS: In brief, we found that a ß1-ß2 loop in the PH domain of kindlin-3, an important part of the canonical membrane phospholipid binding pocket, was also involved in mediating paxillin interaction. Interestingly, the binding sites of paxillin and membrane phospholipids in the PH domain of kindlin-3 were mutually exclusive. Specific disruption of paxillin binding to the PH domain by point mutations inhibited platelet spreading on immobilized fibrinogen while having no inhibition on soluble fibrinogen binding to stimulated platelets. In addition, a membrane-permeable peptide derived from the ß1-ß2 loop in the PH domain of kindlin-3 was capable of inhibiting platelet spreading and clot retraction, but it had no effect on soluble fibrinogen binding to platelets and platelet aggregation. Treatment with this peptide significantly reduced thrombus formation in mice. CONCLUSION: Taken together, these findings suggest that interaction between paxillin and the PH domain of kindlin-3 plays an important role in supporting integrin αIIbß3 outside-in signaling in platelets, thus providing a novel antithrombotic target.

New genera, new species and new records of leafhoppers (Hemiptera: Cicadellidae) from Vietnam.

Recent collecting in northern Vietnam yielded specimens of several new leafhopper species, two of which represent new monotypic genera, and several additional species not previously recorded from Vietnam. The two new genera (Hochiminus n. gen. and Pseudocestius n. gen.) and 15 new species (Abrus digitatus n. sp., Aeternus ninhbinhensis n. sp., Drabescoides bispinosa n. sp., Tenompoella vietnamensis n. sp., Uzelina (Uzelina) vietnamensis sp. n., Hochiminhus tamdaoensis n. sp., Pseudocestius cucphuongensis n. sp., Phlogothamnus pseudorugosus n. sp., Scaphoidella albopunctata n. sp., Bundera onukiiformis n. sp., Carinata arcuata n. sp., Traiguma hamocauda n. sp., Signoretia tamdaoensis n. sp., Amrasca (Quartasca) curvata n. sp., Amrasca (Quartasca) excavata n. sp.) are described and illustrated and comparative notes are provided. An additional 28 species representing 20 genera are newly recorded from Vietnam. Most of the latter were previously recorded only from southern China. The enigmatic species, Tardrabassus pakneunensis Dai Dietrich, previously known from two males collected in Laos in 1918, is newly recorded from Vietnam based on recently collected female specimens. The ovipositor structure of the female confirms placement of Tardrabassus in Iassinae. The female pregenital sternite and ovipositor of Hamulotettix ungulatus Dai Zhang are also illustrated for the first time. A new synonymy is also proposed: Ujna consors Distant, 1908 equals Mileewa puerana Yang Meng, 2010, n. syn.

Rabies post-exposure prophylaxis initiation and adherence among patients in Vietnam, 2014-2016.

BACKGROUND: Adhering to post-exposure prophylaxis (PEP): wound treatment, vaccine, and rabies immunoglobulin (RIG) is a crucial step in preventing rabies mortality. When PEP is widely available, a lack of adherence to the recommended treatment guidelines can also lead to death. Our objective was to understand characteristics associated with adherence to the vaccine regimen and RIG in Vietnam. METHODS: We obtained individual-level data on PEP adherence from registries at 10 sites located in five provinces. From these registries, we extracted epidemiologic characteristics of patients including the timing of PEP initiation and completion. We used descriptive analyses and logistic regression to examine patient characteristics associated with initiation and completion of RIG and vaccine. Based on reported rabies mortality, the government defined provincial rabies burden as medium-burden (<5 and >2 deaths) and high-burden (≥5 deaths). RESULTS: During 2014-2016, 15,646 patients received PEP in our study. Among 14,296 vaccinated patients, only 41.4% (5847) completed their five-dose intramuscular (IM) injections and 81.6% (133) of patients completed their eight-dose intradermal (ID) injections. Approximately 26% of patients received RIG. Patient characteristics associated with vaccine completion were females (44%), <15 years of age (44%), category 1 exposure (68%, bite location on leg (46%), bite from bat (56%), bite from a healthy animal (45%), high-burden province (86%), and district preventive center (49%). Disparities were revealed among provinces, with high-burden provinces having highest (86%) and lowest (7%) vaccine completion rates. CONCLUSIONS AND RELEVANCE: Vietnam has made tremendous progress towards reducing the burden of rabies. However, despite the wide availability of PEP, we found relatively low rates of vaccine completion. Our findings suggest provider training and patient education is needed to ensure appropriate treatment is completed. Moreover, our data suggest changes to information reported through the national surveillance system for monitoring good clinical practice for rabies prevention and control.

Effects of Trang Phuc Linh Plus-Food Supplement on Irritable Bowel Syndrome Induced by Mustard Oil.

Trang phuc linh plus (TPLP) is a food supplement product derived from dried extracts of herbal agents Atractylodes macrocephala, Poria cocos, Paeonia lactiflora, Phellodendron amurense, and added lactobacillus fermentum lysate (ImmuneGamma®) and 5-hydroxytryptophan. TPLP is a functional food used as adjunctive treatment for treating irritable bowel syndrome (IBS). However the biological effect and its mechanism of action in IBS have not been elucidated. In this study, we aimed to determine the pharmacological activities and mode of action of TPLP on IBS animal models. Mice were given a single administration of 5% mustard oil (MO) intracollonically. Acute colitis induction by MO resulted in later development of an IBS-like accelerated upper gastrointestinal transit in mice. Mice were treated with different does of TPLP and controls. Results showed that TPLP at the dose of 654 mg/kg/day given orally significantly decreased intestinal motility (IM) compared with the control animals. The effect was similar to Duspatalin (80 mg/kg/day) (Mebeverine Hydrochloride, an antispasmodic that helps to relieve the pain and discomfort associated with gastrointestinal spasms). Increased TPLP dose (1962 mg/kg/day) had a better effect on relief of IM than Duspatalin (80 mg/kg/day). TPLP also reduced peristalsis frequency and decreased fluid volume and electrolytes excretion in intestine tested in ex vivo models. Overall, TPLP may be an effective nutraceutical supplement for IBS.

Vitamin D deficiency in northern Vietnam: prevalence, risk factors and associations with bone mineral density.

PURPOSE: Vitamin D deficiency has been linked to osteoporosis and also to the risk of cancer, autoimmune disorders and cardiovascular diseases. This study sought to determine the prevalence of, and risk factors for, vitamin D deficiency and its relationship with bone mineral density (BMD) in a Vietnamese population. METHODS: This cross-sectional study involved 269 women and 222 men aged 13-83 years, who were randomly selected from urban and rural areas in northern Vietnam. Serum concentrations of 25-hydroxy-vitamin D [25(OH)D] and parathyroid hormone (PTH) were measured by electrochemiluminescence immunoassay. Vitamin D deficiency was defined as serum 25(OH)D levels below 20 ng/mL. BMD was measured by dual X-ray absorptiometry. RESULTS: The prevalence of vitamin D deficiency in women was 30%, almost two-fold higher than in men (16%). Significant predictors of vitamin D deficiency in women were urban residency (p<0.01) and age less than 30 years (p<0.01), whereas use of contraceptive pills was protective (p<0.01). In men, winter season was the only significant predictor of vitamin D deficiency (p<0.01). In multiple linear regression analysis, serum levels of 25(OH)D were positively associated with BMD in both women (p<0.001) and men (p<0.001). CONCLUSIONS: These data suggest that the prevalence of vitamin D deficiency is high in the Vietnamese population, and that part of this prevalence could be explained by low exposure to sunlight (urban residency and winter season). The high prevalence of vitamin D deficiency should raise the awareness of potentially important health issues such as osteoporosis within the Vietnamese society.